Design

The most striking feature of the Pentax 18-55mm, in comparison to its equivalents from other manufacturers, is a much greater impression of quality to the construction. Despite weighing just 225g, it contrives to feel more like a mid-range lens than a budget kit zoom, with a metal mount and utilisation of quality plastics for both the lens barrel and the zoom and focus rings.

Indeed the manual focus ring easily wins the prize for being the best in its class; it features a long throw and a distance scale, and the front element does not rotate on focusing. Completing the package is the best hood supplied with any kit lens. Overall, this feels like a product which has been designed by photographers, not accountants.

On the camera

The lens handles well on the K10D used for testing; both the zoom ring and manual focus ring fall readily to hand, and the ‘quick-shift’ manual focus option works well for those photographers who aren’t prepared always to rely on autofocus. Overall this is easily the most usable lens in its class from any manufacturer.

Autofocus

Autofocus is driven by a screw-drive system from the camera body, so AF speed, noise and accuracy is fundamentally dependant on the camera used. On our K10D test body, we found focusing to be generally fast and accurate under most conditions, although with a certain tendency to struggle a bit in low light, especially at the telephoto end with its slow maximum aperture of F5.6.

Lens body elements

The lens mount is the Pentax’s standard KAF, using a mixture of electronic and mechanical connections to interface with the camera. To mount the lens, align the red dot with that on the camera body, and twist clockwise.

The black metal lever controls the aperture, and autofocus is driven from the camera body via the screw coupler; 5 1/2 turns are required to travel from infinity to closest focus.

The filter thread is a 52mm, and does not rotate on focusing, which will be a bonus to users of filters such as polarisers.

Decent hood for kit lens shock! The bayonet fitting, petal-type PH-RBA 52mm lens hood is supplied in the box, and mounts by lining up the white marks and twisting about 60 degrees, locking firmly in place. It’s solidly made of black plastic, and reverses neatly for storage, where its 79mm diameter shouldn't cause a problem in most bags.

The hood also features a slide-out ‘window’ for the easy operation of polarising filters. Just take care not to lose it!

Credit where credit is due to Pentax here, this hood design puts all of the other manufacturers to shame, and is genuinely effective at helping to minimise flare.

The lens barrel has 13mm wide, deeply ridged sections directly next to the mount to provide grip when removing or mounting the lens. Unfortunately, in perhaps this lens’s sole concession to marketing, a smooth silver badge proudly proclaiming ’SMC Pentax DA’ rather reduces their effectiveness. Oh well, at least they tried.

The zoom ring rotates 80 degrees clockwise from wide to telephoto, with markings at 18, 24, 35, 45 and 55mm. The rubber grip is 20mm wide and unusually deeply ribbed, and the zoom action smooth and precise. The extension on zooming is just 7mm.

There’s a little wobble to the lens barrel at full extension, but yet again the little Pentax feels much better than most of its competitors here.

The 8mm wide focus ring rotates 110 degrees anticlockwise from infinity to 0.28m, extending the front element by 3mm. The ‘quick-shift’ manual focus system allows tweaking of the focus even when the camera is set to AF. Again the action is smooth and precise, making manual focus perfectly feasible.

There's even a proper distance scale, with markings in both feet and meters. Other manufacturers, please take note.

Reported aperture vs focal length

Here we show the maximum and minimum apertures reported by the camera at the marked focal lengths.

Focal length

18mm

24mm

35mm

45mm

55mm

Max aperture

F3.5

F4.0

F4.0

F4.5

F5.6

Min aperture

F22

F29

F32

F32

F40

The slightest movement of the zoom ring away from the 18mm mark changes the reported maximum aperture to F4.0, perhaps suggesting that the F3.5 designation of this lens is perhaps somewhat marginal.